Community Forums

hshiner · 09-21-2018, 12:28 PM

When I run the generator I can see the amps that we are pulling, but when we are on 50 amp shore power we have a black screen. I’ve checked all the circuit breakers in the panel they are good. I disconnected the wires on the CT’s
There is a voltage across them.
Any suggestions
Thanks in advance

Monico Windsor 2003

TonyMac · 09-21-2018, 12:42 PM

I believe I can only see amps when on 30A or 20A power. My screen is blank as well when on the 50a and genset, except for the little light next to the 50A or genset label.

hshiner · 09-21-2018, 01:08 PM

It had been working for years on 50 amps, just stopped working this week. Should be able to see amps in 20, 30, 50, or gen set

mccrob · 09-21-2018, 04:51 PM

Quote:

Originally Posted by hshiner

It had been working for years on 50 amps, just stopped working this week. Should be able to see amps in 20, 30, 50, or gen set

Not on my 08 Diplomat black screen on 50 amps numbers on all others

JeepTJ5 · 09-22-2018, 08:47 AM

In all my experience the display will blank out in 50 amps because the two legs (when connected to 50 amp shore power) are out of phase and cancel - so the reading would be meaningless.* When on generator the two phases are connected together and in-phase so the reading is accurate. I suppose some generators are split phase 240 volt, but mine is 120v single phase.

(*The current sensor is on the neutral leg.)

10Boomer · 09-22-2018, 10:29 PM

Should be blank on 50amp shore-power

hshiner · 09-23-2018, 02:05 AM

Quote:

Originally Posted by 10Boomer

Should be blank on 50amp shore-power

I need to apologize as I thought I saw that it was reading amps when connected to 50 amps. Then it is working properly.

sdennislee · 09-23-2018, 03:00 AM

It is working properly, should be blank on 50A.

sticky · 09-26-2018, 06:43 PM

I had posted this explanation a while back for someone else -

The EMS system only measures the return current on the neutral wire. The reason you don't get a readout when connected to 50 amp shore power is because the two phases (hot legs) are 180 deg out of phase with each other (this is how you get your 240 volts), this causes a canceling effect on the neutral. So for example, if you had 10 amps on one leg and 2 amps on the other, the neutral return current would only read 8 amps. For this reason the readout is deactivated when being used with 50 amp shore power source as it would be innaccurate. The reason it works with some generators and not others is because many smaller rv generators, generally up to 8000 KW, put out only one 120 volt leg or sometimes two 120 volt legs but they are not out of phase with each other (no 240 volt) so the return current on the neutral is additive thus allowing for an accurate amperage readout, so they do not disable it under this condition. This is also why you will generally see an oversized neutral between the generator, transfer switch, an electrical panel as it is needed to carry the load of both hot legs. Some larger generators do generate a true 120 / 240 volt output just like your home and these also will not have a amperage read out as it is disabled because of the canceling effect as previously mentioned. Newer systems and some other brands actually measure each hot independently and add the total so they don't suffer from this issue.

So basically any time your running on a 120/240 power source it will not readout. Hope this long winded post helped and didn't confuse you more. Lol